/* 
 *  Copyright 2012 CodeMagi, Inc.
 * 
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package com.codemagi.servlets;

import java.io.*;
import javax.servlet.http.*;
import org.apache.log4j.*;

/**
 * HttpSessionListener to keep track of the number of active sessions in your Context.
 * To use, add a listener definition to web.xml:
 *
 * <code>
 *     <listener>
 *        <listener-class>com.codemagi.servlets.SessionTracker</listener-class>
 *     </listener>
 * </code>
 */
public class SessionTracker implements HttpSessionListener, Serializable {

    Logger log = Logger.getLogger(this.getClass());

    private static int numSessions = 0;

    public void sessionCreated(HttpSessionEvent e) {
        log.debug("NEW SESSION");
        numSessions++;
    }

    public void sessionDestroyed(HttpSessionEvent e) {
        log.debug("SESSION DISPOSED");
        if (numSessions > 0) numSessions--;
    }

    public static int getNumSessions() {
        return numSessions;
    }

}
